用蔗糖、奶粉和经蛋白酶水解后的玉米胚芽液，通过乳酸菌发酵可生_爱下问搜题

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问题单项选择题

用蔗糖、奶粉和经蛋白酶水解后的玉米胚芽液，通过乳酸菌发酵可生产新型酸奶。下列相关叙述错误的是( )

A．蔗糖消耗量与乳酸生成量呈正相关
B．酸奶出现明显气泡说明有杂菌污染
C．应选择处于对数期的乳酸菌接种
D．只有奶粉为乳酸茵发解提供氮源

答案

参考答案：D

解析：乳酸菌利用蔗糖发酵产生乳酸，代谢产物——乳酸的生成量与原料——蔗糖的消耗量成正相关。乳酸菌发酵只产生乳酸，不产生CO₂，酸奶出现明显气泡说明有杂菌进行了无氧呼吸产生了CO₂。对数期的细菌个体特征和生理特性稳定，常作为生产菌种。经蛋白酶水解后的玉米胚芽液，含有氨基酸，可为乳酸菌发酵提供氮源。

单项选择题

文件系统的主要目的是

A．实现对文件的按名存取

B．实现虚拟存储

C．提高外存的读写速度

D．用于存储系统文件

完形填空

阅读下面短文，掌握其大意，然后从36—55各题所给的四个选项(A、B、C和D)中，选出最佳选项，并在答题卡上将该项涂黑。

Last night, when I was driving back home, I noticed a hitchhiker(搭便车的人) who was having no luck getting a ride. I rolled down my 36 and signed to the man to my car. I asked him where he was 37 and he told me he needed a 38 to his doctor’s office which would close in 15 minutes. I told him to 39 and he gratefully did so.
40 he got in he told me that he was a 41 and went out to sea for weeks at a time. He took medicine for his nerves and 42 to get another prescription(处方) before he left on the boat. He said that he had prayed (祈祷) 43 would stop for him so he could be there before the 44 office closed. With some 45 driving we managed to make it there in about 10 46. I then asked him how he 47 on getting back home and he said he could walk. “I’ll patiently 48 for you and bring you back,” I told him. He 49 me and said he should only be about 15 minutes.
Afterwards he got back in my 50 and tried his hardest to pay me back: offering me dinner, gas money, even offering to ship me 40 lbs of scallops (海扇贝)! I 51 refused, gave him a smile card and asked him to help someone else the next time he had a 52. I drove him back to where I had picked him up and 53 one more “thank you” he was on his way.
I feel that the universe 54 provides us with what we need. In the man’s 55 it was a ride, in mine the opportunity to help someone else.

D．Just before

A．teacher’s

C．manager’s

D．captain’s

C．immediately

D．surprisingly